Schauder estimates for steady compressible Navier-Stokes equations in bounded domains
In this paper sufficient optimality conditions are established for optimal control of both steady-state and instationary Navier-Stokes equations. The second-order condition requires coercivity of the Lagrange function on a suitable subspace together with first-order necessary conditions. It ensures local optimality of a reference function in a -neighborhood, whereby the underlying analysis allows to use weaker norms than .
In this paper sufficient optimality conditions are established for optimal control of both steady-state and instationary Navier-Stokes equations. The second-order condition requires coercivity of the Lagrange function on a suitable subspace together with first-order necessary conditions. It ensures local optimality of a reference function in a Ls-neighborhood, whereby the underlying analysis allows to use weaker norms than L∞.
We consider regular solutions to the Navier-Stokes equation and provide an extension to the Escauriaza-Seregin-Sverak blow-up criterion in the negative regularity Besov scale, with regularity arbitrarly close to . Our results rely on turning a priori bounds for the solution in negative Besov spaces into bounds in the positive regularity scale.
The most important result stated in this paper is a theorem on the existence of global solutions for the Navier-Stokes equations in Rn when the initial velocity belongs to the space weak Ln(Rn) with a sufficiently small norm. Furthermore, this fact leads us to obtain self-similar solutions if the initial velocity is, besides, an homogeneous function of degree -1. Partial uniqueness is also discussed.
We consider the Cauchy problem for the three-dimensional Navier-Stokes equations, and provide an optimal regularity criterion in terms of and , which are the third components of the velocity and vorticity, respectively. This gives an affirmative answer to an open problem in the paper by P. Penel, M. Pokorný (2004).
Nous exposons dans cet article l'analogue de ces résultats d'existence pour l'équation de Navier-Stokes [Cannone (4), Cannone et Planchon (27, 5, 28)], mais sur un domaine extérieur Ωε, complémentaire d'un compact à bord lisse. Les deux difficultés nouvelles qui se présentent sont l'absence d'une représentation explicite en Fourier du semi-groupe associé à l'opérateur de Stokes et la nécessité de transposer la notion d'espace de Besov homogène.